This disclosure relates to rack-and-pinion steering systems, and more particularly relates to rack-and-pinion steering systems having dual racks.
In conventional steering systems, the operator controls the travel direction of the vehicle with the aid of a steering wheel. This steering wheel is mechanically connected, usually through a gear assembly, to the road wheels. To aid the operator, many systems utilize an auxiliary system to generate an additional force that is transmitted to a steering gear assembly. The additional force reduces the effort required by the operator in adjusting the travel direction of the vehicle. Typically, this auxiliary force is generated by either a hydraulic drive or an electric motor.
Because the steering wheel is connected directly to the road wheels, the resulting mechanical assembly that provides the connection can be quite bulky, complicated and expensive to produce. Therefore, it is desirable to provide a steering system that is less bulky, complicated and expensive than a conventional mechanical system while still providing similar benefits to the operator.
It is often beneficial to change the steering angle of one road wheel at a rate different from that of the other road wheel. Although a steering system employing two separate road wheel actuators is not restricted to turning both wheels at the same rate, it is desirable to develop a steering system needing only a single actuator that also permits differing angles between the two steered road wheels. In addition, it is desirable that such a unit act directly on the steered wheels without incurring an inefficient mechanical disadvantage or bulky packaging disadvantage due to extended Ackerman-type steering arms.
The above discussed and other drawbacks and deficiencies of the prior art are overcome or alleviated by a dual variable-tooth rack and single pinion steering system. In an exemplary embodiment, a dual variable-tooth rack and single pinion steering system includes a first elongated rack having an inner end, an outer end, and a set of teeth with a predetermined variable tooth profile located between its ends; and a second elongated rack having an inner end, an outer end, and a set of teeth with a predetermined variable tooth profile located between its ends. In addition, the steering system has a pinion disposed to engage the inner end of the first rack and the inner end of the second rack. A set of rack displacements is thereby defined between the outer end of the first rack and the outer end of the second rack that corresponds to a set of variable steering angles between a pair of steered wheels.